Supplemental Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2012	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income (loss)	$ 665	$ 632			$ 1,385	$ 1,086
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities					(2,096)	(2,151)
Provision for doubtful accounts	1,035	728			1,681	1,579
Depreciation and amortization	469	454			942	901
Income taxes					(101)	(94)
Gains on sales of facilities	5	(11)			(4)	(32)
Losses on retirement of debt	125	226			125	226
Legal claim costs			$ 78	$ 175		78
Amortization of debt issuance costs					19	23
Share-based compensation					103	77
Equity in earnings of affiliates	(10)	(9)			(29)	(18)
Other					21
Net cash provided by operating activities					2,075	1,693
Cash flows from investing activities:
Purchase of property and equipment					(1,004)	(913)
Acquisition of hospitals and health care entities					(95)	(27)
Disposition of hospitals and health care entities					22	32
Change in investments					67	43
Other					1	1
Net cash used in investing activities					(1,009)	(864)
Cash flows from financing activities:
Issuance of long-term debt					4,048	3,502
Net change in revolving credit facilities					(300)	340
Repayment of long-term debt					(3,644)	(3,482)
Distributions to noncontrolling interests					(237)	(197)
Payment of debt issuance costs					(33)	(49)
Repurchases of common stock					(940)	(750)
Income tax benefits					197	75
Other					(50)	(24)
Net cash used in financing activities					(959)	(585)
Change in cash and cash equivalents					107	244
Cash and cash equivalents at beginning of period			414		566	414
Cash and cash equivalents at end of period	673	658			673	658
Eliminations [Member]
Cash flows from operating activities:
Net income (loss)	(603)	(516)			(1,226)	(894)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in earnings of affiliates	603	516			1,226	894
HCA Holdings, Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)	507	483			1,098	830
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities					21	13
Income taxes					(101)	(94)
Losses on retirement of debt	122				122
Amortization of debt issuance costs					2	2
Share-based compensation					103	77
Equity in earnings of affiliates	(603)	(516)			(1,226)	(894)
Other					34
Net cash provided by operating activities					53	(66)
Cash flows from financing activities:
Repayment of long-term debt					(1,632)
Repurchases of common stock					(940)	(750)
Changes in intercompany balances with affiliates, net					2,354	756
Income tax benefits					197	75
Other					(32)	(15)
Net cash used in financing activities					(53)	66
HCA Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)	(373)	(485)			(744)	(873)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities					22	(32)
Losses on retirement of debt	3	226			3	226
Legal claim costs						78
Amortization of debt issuance costs					17	21
Other						1
Net cash provided by operating activities					(702)	(579)
Cash flows from financing activities:
Issuance of long-term debt					4,048	3,502
Net change in revolving credit facilities					(300)	340
Repayment of long-term debt					(1,971)	(3,441)
Payment of debt issuance costs					(33)	(49)
Changes in intercompany balances with affiliates, net					(1,042)	227
Net cash used in financing activities					702	579
Subsidiary Guarantors [Member]
Cash flows from operating activities:
Net income (loss)	760	692			1,491	1,269
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities					(1,360)	(1,258)
Provision for doubtful accounts	550	394			846	931
Depreciation and amortization	223	224			453	442
Gains on sales of facilities	5	(11)			(4)	(32)
Equity in earnings of affiliates	(2)	(1)			(3)	(2)
Other					(2)
Net cash provided by operating activities					1,424	1,352
Cash flows from investing activities:
Purchase of property and equipment					(470)	(583)
Acquisition of hospitals and health care entities					(16)	(2)
Disposition of hospitals and health care entities					14	25
Change in investments					6	26
Other					(6)
Net cash used in investing activities					(472)	(534)
Cash flows from financing activities:
Repayment of long-term debt					(24)	(25)
Distributions to noncontrolling interests					(46)	(27)
Changes in intercompany balances with affiliates, net					(839)	(663)
Net cash used in financing activities					(909)	(715)
Change in cash and cash equivalents					43	103
Cash and cash equivalents at beginning of period			112		87	112
Cash and cash equivalents at end of period	130	215			130	215
Subsidiary Non-Guarantors [Member]
Cash flows from operating activities:
Net income (loss)	374	458			766	754
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities					(779)	(874)
Provision for doubtful accounts	485	334			835	648
Depreciation and amortization	246	230			489	459
Equity in earnings of affiliates	(8)	(8)			(26)	(16)
Other					(11)	(1)
Net cash provided by operating activities					1,300	986
Cash flows from investing activities:
Purchase of property and equipment					(534)	(330)
Acquisition of hospitals and health care entities					(79)	(25)
Disposition of hospitals and health care entities					8	7
Change in investments					61	17
Other					7	1
Net cash used in investing activities					(537)	(330)
Cash flows from financing activities:
Repayment of long-term debt					(17)	(16)
Distributions to noncontrolling interests					(191)	(170)
Changes in intercompany balances with affiliates, net					(473)	(320)
Other					(18)	(9)
Net cash used in financing activities					(699)	(515)
Change in cash and cash equivalents					64	141
Cash and cash equivalents at beginning of period			$ 302		479	302
Cash and cash equivalents at end of period	$ 543	$ 443			$ 543	$ 443